California Clapper Rail (image) University of California - Davis Caption A California Clapper Rail stands beside invasive Spartina, a salt marsh cordgrass, in San Francisco Bay. The endangered bird is threatened by both the removal and existence of the invasive plant. Credit Robert Clark Usage Restrictions Provide credit. Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.